1. Field of the Invention
The invention relates to an upright composite common mode coil assembly that facilitates automatic discharging on a production line, reduces the layout area of a circuit board, and facilitates stacking of a plurality of these assemblies; the assembly also has no protruding wires.
2. Description of the Prior Art
Conventionally, a transformer having a common mode choke and a differential mode choke, in operation, receives an AC voltage source, which is passed through the common mode choke and the differential mode choke to a rectifier, and a DC voltage source is outputted. The common mode choke and the differential choke are used to cancel common mode noise and differential mode noise. A reference is made here to a TW Patent Publication No. I341540, titled “Composite Common Mode Coil”, which includes: a base, a coil carrier, and an iron core. The base has two receiving slots and a separating slot located between the two receiving slots. The coil carrier is provided with two bobbins, each having a plurality of coils wound around the outer circumference of the bobbin, and the two bobbins are respectively disposed in the two receiving slots. The iron core has two opposite sides and is positioned in the separating slot with their sides abut against the bobbins. A current is passed through the plurality of coils in each bobbin, resulting in a leakage inductance formed in the bobbin carrier. The magnitude of the leakage inductance can be changed by adjusting the surface area of the sides. However, the coils in this publication are arranged side by side horizontally, so they will occupy a large area on a circuit board when they are actually connected to the circuit board, and as a result of this, the area of the circuit board cannot effectively reduced. Meanwhile, when the coils are in operation, they will produce heat, but due to the horizontal arrangement of the coils, the coil are in proximity to the circuit board, which will not allow air to circulate easily. The poor heat dissipation leads to higher temperature and lower efficiency.
In order to address the issue associated with large-sized transformers, another type of transformer has been proposed, referring to, for example, a TW Patent Publication No. M479500, titled “Vertical Surface-Mounted Transformer”, which includes an iron core, at least two groups of coils, and ferromagnetic colloid surrounding the coils. The iron core includes a top portion, a base portion remote from and opposite to the top portion, and a recessed winding portion connecting the top portion and the base portion. Each of the two groups of coils respectively has at least two end contacts, and is wound around the recessed winding portion. It is characterized in that the top portion is formed with a flat surface to facilitate handling by suction, and the base portion has six bottom electrodes; each of the two end contacts from each group of coils is respectively connected to a bottom electrode. However, in this publication, although the iron core is arranged in an upright position, all the coils are horizontally arranged in parallel as viewed from a horizontal angle. The upright iron core further hinders circulation of air among the groups of coils. The poor heat dissipation leads to higher temperature and lower efficiency or even a burnt device.
In view of the above drawbacks of the conventional techniques, the inventors endeavored to find a solution and have finally come up with the present invention to address the aforementioned shortcomings.